The long term objective of this application is to delineate at least some of the factors controlling puberty in the male. Most previous work has assumed that alterations in the brain lead to alterations in pituitary function which in turn induce gonadal maturation and sexual development. Recent work has suggested that gonadal steroids may be involved in the induction of some of the changes that occur in pituitary function. One of these is the development of a self-priming effect of LHRH on LH secretion. This application proposes to study the effect of acute castration and acute steroid administration on the expression of the self-priming effect at various times during the sexual development of the male rat. Rats will be anesthetized with ketamine HCl, castrated, treated with steroid and then primed with 3 injections of 10ng LHRH/100g BW or saline at 30 min. intervals. A blood sample will be obtained 30 min. after the last priming injection followed by a 50ng LHRH/100g BW challenge injection. A final blood sample will be obtained 10 min. after the challenge injection. Steroids to be examined include testosterone, 5Alpha-dihydrotestosterone, androstenedione, 5Alpha androstane - 3Alpha, 17Beta diol, 5Alpha androstane - 3Beta, 17Beta diol and estradiol. Other experiments will examine the ability of pituitaries obtained from male rats at various stages of sexual development to show a self-priming effect in vitro. Other experiments will explore the possibility that LHRH may also have a self-priming effect on FSH secretion. Male rats of various ages will be used. Steroid involvement in such an effect will also be investigated. The possibility that AlphaMSH may be involved in the release of LH and/or FSH during the sexual maturation of the male rat will also be examined.